Check out this post.
This makes a pretty convincing argument for why the highly supportive, high-tech athletic shoes can actually contribute to injuries. In brief, the knee-leg-foot structures are built to sense and absorb the impact of activities like running. By lying to them about the actual impact (by absorbing it), the shoes actually make the body pound harder on the joints. If you run barefoot and/or with minimal protection to the sole, you will be a whole lot better off, since you will let the body do what it does.By protecting something that is designed to take impact, we are actually weakening it.
Some very interesting studies have been quoted, the most obvious of which is that barefeet cultures seldom report the kind of foot problems that are common in shoe wearing cultures.